**1. Introduction**

Recent developments in the food packaging industry have revealed that biopolymerbased edible films have great potential to replace plastics. The different characteristics

**Citation:** Bhatia, S.; Al-Harrasi, A.; Shah, Y.A.; Altoubi, H.W.K.; Kotta, S.; Sharma, P.; Anwer, M.K.; Kaithavalappil, D.S.; Koca, E.; Aydemir, L.Y. Fabrication, Characterization, and Antioxidant Potential of Sodium Alginate/Acacia Gum Hydrogel-Based Films Loaded with Cinnamon Essential Oil. *Gels* **2023**, *9*, 337. https://doi.org/ 10.3390/gels9040337

Academic Editors: Aris Giannakas, Constantinos Salmas and Charalampos Proestos

Received: 12 March 2023 Revised: 4 April 2023 Accepted: 10 April 2023 Published: 15 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

of edible films, such as their non-toxicity, biodegradability, and safety, make them a feasible option for food packaging material [1]. Hydrogels are used in a broad range of applications due to their characteristic properties such as hydrophilicity, non-toxicity, and biocompatibility [2–4]. Sodium alginate (SA) is a natural hydrophilic polysaccharide and has been used in the fabrication of biopolymer films due to its excellent film-forming properties [5–7]. Sodium alginate-based edible films have demonstrated superior mechanical properties along with good transparency [8]. Sodium alginate is a common hydrogel polymer that tends to form hydrogel via substituting sodium ions of the guluronic acid residues. Despite their good mechanical properties, edible films made from sodium alginate are limited by their high hydrophilicity and poor heat stability [9]. Combining SA with various other polymers is one approach that has been investigated extensively to overcome these challenges.

Acacia gum, also known as gum Arabic, is a gummy exudate obtained from the branches and trunk of the Acacia senegal and Acacia seyal plant species [10]. AG is a watersoluble, highly branched polysaccharide extensively used as a thickener, stabilizer, and emulsifier in the food industry [11]. It has been employed in the production of edible films due to its biocompatibility, renewability, non-toxicity, pH stability, low cost, high solubility, and gelling properties [12]. AG can be used to make edible films; however, it poses several challenges, such as its poor mechanical attributes, its high hydrophilicity, and its poor barrier features [13]. However, the preparation of composite films consisting of SA and AG could be an option to enhance the physiochemical properties of the resulting films. Over the past few years, numerous studies have highlighted the advantages of incorporating bioactive compounds such as essential oils in edible films for improved physiochemical and antioxidant attributes [14–16]. In the current study, cinnamon essential oil (CEO) was incorporated in the SA–AG composite hydrogel-based films due to its vast industrial and medicinal applications, such as antimicrobial and antioxidant agents [17]. The essential oil of cinnamon has a variety of significant chemical constituents, the most prominent of which are the compounds aldehyde and alcohol, along with trans-cinnamaldehyde and eugenol [17–19]. Zhou et al. [20] studied the physiochemical properties of cassava starchbased edible films that were loaded with cinnamon essential oil. After the assessment, it was found that the films' barrier properties, crystallinity, and elongation at break (EAB) were considerably enhanced and that there was also an improvement in their thermal stability [20].

Given its antimicrobial and antioxidant characteristics, cinnamon is widely acknowledged as a safe food preservative [21]. The objective of the current study is to assess the physiochemical and antioxidant properties of composite hydrogel-based films based on SA and AG, which have been loaded with varying concentrations of cinnamon essential oil.
